Atomic disorder, phase transformation, and phase restoration inCo3Sn2

The behavior of the intermetallic compound ${\mathrm{Co}}_3$ ${\mathrm{Sn}}_2$ upon ball milling was studied by x-ray diffraction, high-field-magnetization measurements, and subsequently by differential scanning calorimetry. It turns out that starting from the stoichiometric-ordered compound, mechanical attrition of ${\mathrm{Co}}_3$ ${\mathrm{Sn}}_2$ generates atomic disorder in the early stage of milling. The nonequilibrium phase transformation from the low-temperature phase with orthorhombic structure to the high-temperature phase with a hexagonal structure was observed in the intermediate stage of milling. It was accompanied by the creation of increasing atomic disorder. After long milling periods, the phase transformation was completed and the atomic disordering became saturated. All the physical parameters measured in the present work remained constant during this period. The above outcome was confirmed by comparison with the high-temperature phase thermally induced by quenching. The good agreement of the results obtained by different techniques proves that the ball milling generates well-defined metastable states in ${\mathrm{Co}}_3$ ${\mathrm{Sn}}_2$.